The treatment of only environmental Streptococci clinical mastitis cases reduced antibiotic use, days out of the tank, recurrence of clinical mastitis and a tendency to reduce culling

Abstract Text:

This study objective was to compare antibiotic use, clinical and bacteriological outcomes for selective treatment of only clinical cases where environmental streptococci were isolated versus blanket therapy. Cows with mild or moderate clinical mastitis (CM) from a California Central Valley dairy herd were assigned to either a) a positive-control treatment group (PC) or b) a laboratory-culture-based treatment group (CB). Quarter cases assigned to PC received immediate intramammary (IMM) treatment with ceftiofur (Spectramast LC; Zoetis Inc., New York, NY) and repeated once a day for a total of three days.  Quarters assigned to CB underwent culture over a 24 h period at DairyExperts Laboratory (DairyExperts Inc, Tulare, CA).  Only quarters showing environmental streptococci growth were treated the next day with the same therapy as cases assigned to PC. Mixed Models were used with cow included as a random effect. A total of 276 quarter cases of clinical mastitis from 223 cows were enrolled into the study. Results are summarized on Table 1.  The selective treatment of only CM cases from which environmental streptococci were isolated resulted in about a two-thirds reduction both in the number of cases treated and in the number of IMM tubes used, as well as a reduction of one day out of the tank.  Interestingly, CM recurrence was significantly lower and removal from herd tended to be lower when only environmental streptococci were treated with IMM antibiotics.

Keywords: Clinical mastitis, selective treatment, streptococcus